System and method for connection of photovoltaic arrays in series and parallel arrangements

Abstract

A system and method for selectively connecting photovoltaic (PV) arrays of a PV power system in series and parallel arrangements is disclosed. A DC-to-AC power inverter in the PV power system is electrically coupled to a plurality of PV arrays to receive a DC output therefrom and invert the DC output to an AC output, with the DC-to-AC power inverter including a DC link that receives the DC output from the plurality of PV arrays. A contactor arrangement is positioned between the plurality of PV arrays and the DC-to-AC power inverter, with the contactor arrangement including a plurality of contactors that are switchable between an on state and an off state to selectively connect the plurality of PV arrays to the DC-to-AC power inverter in a specified arrangement, so as to control a level of DC voltage received by the DC-to-AC power inverter from the plurality of PV arrays.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates generally to photovoltaic (PV) power systems and, more particularly, to a PV array that incorporates a set of contactors that are selectively operated in order to provide an increased working voltage for a PV inverter in the PV power system without the use of DC-DC converters.[0002]PV power systems are power systems that employ a plurality of solar modules to convert sunlight into electricity. PV systems include multiple components, including photovoltaic modules, mechanical and electrical connections and mountings, and means of regulating or modifying the electrical output. One common arrangement in PV systems is for several PV modules to be connected in series to form a PV string, with multiple PV strings in a PV system then being combined in parallel to aggregate the current in a PV array. The output of multiple PV arrays can then be combined by way of a combiner box that aggregates the DC power from the PV arrays and...

AI Technical Summary

Benefits of technology

[0008]The present invention provides a system and method for system and method for selectively connecting PV arrays in a PV power system in series and parallel arrangements, so as to eliminate the need for a DC-DC conversion in a PV inverter and improve efficiency in the PV power system.

Problems solved by technology

With respect to typical two stage PV inverters, one drawback is that such inverters are inherently less efficient and more costly due to the second stage.

That is, the efficiency of the two-stage inverter is a multiple of the individual stage efficiencies, with each stage typically causing one-half of the system losses.

Another recognized drawback with existing PV array and PV inverter arrangements is that the DC power and voltage generated by the PV array groups can widely vary, as the amount of DC power / voltage generated thereby is dependent on the temperature at which PV arrays operate and the amount of solar irradiation received by the PV arrays.

Accordingly, the PV inverter may not always be operating at an optimal working voltage if the amount of DC voltage received from the PV array is less than the optimal working voltage level.

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